Exedra's Balder tool passes rigorous testing

Exedra has developed a cost-effective and versatile method to verify the integrity of downhole barriers for permanently plugging oil and gas wells using tracer gas. On March 28th, the company successfully demonstrated the method and functionality of the tool ‘’Balder’’ on the Gullfaks field.

Exedra, a Norwegian start-up and member of Energy Transition Norway, has developed a cost-effective and versatile method to verify the integrity of downhole barriers for permanently plugging oil and gas wells by utilizing tracer gas. On March 28th, the company successfully demonstrated the functionality of the tool called Balder on the Gullfaks field, in well GF-A11.

Today, no effective and unambiguous method exists to verify that the plugged wells are leak-tight. Exedra's technology opens up new possibilities for well-plugging solutions that drive down costs and environmental footprint related to P&A.

The challenge of plugging and abandoning oil and gas wells

A large number of oil and gas wells needs to be permanently plugged and abandoned post-production globally. Without a means to check that the plugs won’t leak hazardous gas and fluid over time, operators have no choice but to employ "overkill" solutions that are several times more expensive than what is necessary to plug the well.

– The cost of plugging one well alone on the Norwegian Continental Shelf might be 100 million Norwegian kroner says Exedra inventor and CEO, Bernt Pedersen.

The importance of verifying the integrity of downhole barriers

The lack of a reliable method to verify the integrity of downhole barriers for permanently plugging oil and gas wells has been a longstanding issue in the industry. Employing multiple barriers and stringent requirements to ensure leak-free wells can be expensive, time-consuming, and may have an unnecessarily large environmental footprint.

A new, efficient, and sensitive method to verify permanent barriers would make it easier for other companies to introduce their new, cost-effective, and often shorter barrier solutions to the market.

The Balder tool: How Exedra's solution works

Exedra's Balder tool uses a tracer gas, a rare gas that does not exist naturally in the reservoir. By applying this gas under pressure underneath the plug that is to be tested, and subsequently measuring whether the gas can be detected above the plug, Exedra can verify whether the plug leaks or not.

The tool is 2.5 meters long and 12 centimeters in diameter. The verifying method is fast, extremely sensitive, low-cost, and unambiguous. It is a generic method that can be applied to various plugging materials and geometries, enabling the O&G industry to introduce lower-cost and flexible new solutions for the permanent plugging of wells. It can also be used when plugging wells on wireline, without the use of a drilling rig.

The development process: From idea to successful field test

Exedra’s CEO, Bernt Pedersen, saw many projects developing different plugging methods, but none that solved the crucial problem of verifying that the plugs are 100% leak tight, which makes it challenging for them to be widely adopted.

The project was initially financed by ConocoPhillips, Innovation Norway and Regionalt Forskningsfond  After positive results from a feasibility study, Validé,  Equinor and later also AkerBP joined the project.

Pedersen has worked on the project since 2017.  Prior to testing the method offshore, the method has been tested twice at the Ullrigg test rig outside Stavanger.  The tool used at the Gullfaks field demonstration has been completely redesigned since the first prototype was tested at Ullrigg. The development project har used DNV as a third-party verified throughout the whole process.

– The purpose of the test at Gullfaks was to demonstrate that the technology works in a real well, using commercially available detection systems.  It is critically important to have our operators' backing and access to testing in their wells. On the Gullfaks test, Exedra provided the downhole tool, and Schlumberger supplied the hyper-sensitive detector solution that captured the tracer gas released by our tool, says Pedersen.

An important step towards a more sustainable industry

Egil Aanestad, CEO of Energy Transition Norway, congratulates Exedra with the good news.

– Our mandate as a cluster is to bring world-leading expertise and technology environments together to accelerate innovation in the energy transition. Exedra's successful development of the Balder tool aligns perfectly with our goal, as it provides a breakthrough solution that can significantly reduce costs and environmental impact in the plugging and abandonment of oil and gas wells.

– This is an important step towards creating a more sustainable industry, and we are proud to have Exedra as a member of our cluster, and the development of the Balder Tool as one of our cluster projects.